Power transmitting mechanism



A. Y. DODGE POWER TRANSMITTING MECHANISM Filed Oct. 10, 1952 Aug. 6,1957 2,801,721

r INVENTOR, BY W%Q0@e,

ATTORNEYS.

United States Patent POWER TRANSMITTING MECHANISM Adiel Y. Dodge,Rockford, Ill. Application October 10, 1952, Serial No. 314,155 Claims.(Cl. 192-53 This invention relates to power transmitting mechanisms andmore particularly to a positive clutch'construction for the transmissionof torque.

Positive tooth clutches have been used in many types of powertransmitting mechanisms to control the transmission of torque and tochange driving ratios and conditions. It is highly desirable that suchclutches be easy to engage and disengage even while under load and thatthey be held positively in engagement during driving. I e In mycopendingapplication Serial No. 213,141, filed February 28, 1951, now Patent No.2,735,528, there ice tion will be more readily apparent when viewed inconnection with the accompanying drawings in which:

clutch teeth embodying the invention;

disclosed and claimed a clutch which satisfies the require ments foreasy disengagement under load and which is held positively in engagementduring driving. This clutch can be engaged relatively easily when thedifference in relative rotation of the parts is small but is difficultto engage when the speed and torque differences are substantial. Undersuch extreme conditions the clutch teeth may be damaged and aresubjected to wear. t

Oneofthe objects of this invention is to provide a power transmissionmechanism, including a positive clutch in which the teeth are protectedagainst damagedueto engagement at too large a difference in speed, andin which are provided means to help bring about synchroni zation andwhich can easily be disengaged under load and is held positively inengagement during torque transmission. i i i Another object is toprovide a power transmitting mechanism in which the speed of the partsis substan tially synchronized by friction means before engagement ofthe teeth and in which the teeth friction means during initial engagingmovement.

Still another object is to provide a power transmitting mechanism inwhich a synchronizer ring frictionally engages one 'of the parts and isprovided with relatively thin teeth projecting radially between theteeth on the parts and which are engaged by one of the parts prior to engagement thereof with the other part. i

According to one feature, engaging and disengaging movement of the partsis controlled by a cam mechanism having two stepped positions, one tourge the synchronizing ring teeth only into effective engagement and theother to hold the main clutch teeth on the parts in engagement.

A further object is to provide a power transmitting mechanism in whichthe clutch teeth are formed with helically generated surfaces providingat least a line contact in all relative positions thereof.

According to one feature of the invention, the clutch teeth are formedwith rounded corners which are also relatively rapid are shaped to loadthe Figure 3 is a partial end view of one of the clutch ele mentsshowing the tooth form; and

Figure 4 is a partial enlarged section showing the actuatand lockingmechanism.

As illustrated in Figure 1, the invention is embodied in a two speed andreverse transmission mechanism having an input shaft 10 which may bedriven mechanically from an engine or the like or which may be drivenhydraulically through a hydraulic torque converter, a portion of whichis shown at 11. The input shaft 10 drives a pinion 12 meshing with apinion 13 on a lay shaft 14 which also carries pinions 15 and 16. Anoutput shaft 17 is arranged axially with the input shaft 10 and may haveits inner end supported on a bearing 18 carried by a reduced extensionof the input shaft.

Driven gears 19 and 21 are mounted on the output shaft 17 for freerotation relative thereto and may be connected to the output shaft byclutch mechanism as described hereinafter. The gear 19 meshes with thegear 15 and is mounted as shown on a pair of oppositely taperedsynchronizer rings 22 and 23 which are freely rotatable on the outputshaft 17 and have a limited axial movement thereon. As shown, thesynchronizing ring 22 is held against movement to the left by splines 24on the output shaft and movement of the synchronizing ring 23 to theright is limited by a snap ring 25. Springs 26 urge the synchronizerrings toward each other into frictional gripping engagement with taperedsurfaces on the interior of the gear 19 with a relatively light degreeof force.

*The gear 21 constitutes a reverse gear and may mesh with a reverseidler 27 which in turn meshes with the gear 16. Preferably the gears 16,21, and 27 are formed with helical teeth so that driving torque willproduce an. end thrust on the gear 21 for a purpose to appear more fullyhereinafter. s

Either the driving gear 12 or the gear 19 may be connected to the outputshaft 17 by a double acting clutch mechanism including a shiftablesleeve 28 slidably splined on the splines 24. The sleeve 28 is formed atits opposite ends with elongated clutch teeth 29 to mesh withcomplementary clutch teeth 31 on the driving gear 12 and 32 on the gear19. The teeth 31 and 32 may be of identical configuration and arepreferably shorter axially than the teeth 29, as shown.

In order to synchronize the speeds of the clutch parts before engagementof the teeth thereof, a synchronizing ring 33 is fitted into a taperedcavity in the driving gear 12 and is urged inward thereof by a spring34. The synchronizing ring 33 may be identical with the synchronizingring 22 and each of them is formed with an annular series of teeth 35projecting radially between the sets of clutch teeth 29 and 31 and 29and 32. When the sleeve 28 is shifted toward one of the other of thegears to engage the desired clutch, the teeth 29 thereon will firstengage the synchronizer teeth 35 and will exert axial pressurethereon toincrease engagement between the synchronizer ring and the cooperatinggear member. When the teeth 29 have engaged the synchronizer teeth 35the synchronizer ring will turn with the sleeve 28 and throughfrictional engagement with its corresponding gear will tend to bring thehelically generated so that line contact between the corner portions ofthe teeth is maintained during initial engagement and finaldisengagement.

The above and other objects and features of the inven synchronousconditions and for easy disengagement under load. As shown, the clutchteeth 29, 31, and 32 have their sides tapered axially toward each otherso that when they are in engagement the torque load thereon will producean axial thrust tending to disengage them. The tooth angle may beselected, preferably on the'order of 11 to 14 /2", to provide sufiicientthrustto'overcome tooth friction and friction in the splines so that thesleeve 28 can easily be shifted to disengage theclutcheven when asubstantial torque load is present. T he syn'c hronizer teeth 35 asshown are relatively thin axially and may also be tapered to fit betweenthe teeth 29 so that the teeth 29 can project between them into meshwith the clutch teeth 31 and 32. Preferably-all of'the-teethhave theircorners at their outer tips rounded sothat-they can slide over eachother easily while they are being :brought intoengagement-and so thatan'axial thrust will be produced especially on thesynchronizer rings.

, 'According to another feature of the inventionthe engaging faces ofall of the teeth are helically formed to provide at least a line contactin all relative positions thereof. In other words, the faces of theteeth including the rounded cornersthereof are generated bylines'perpendicular to the axis and passing through thetooth faces. Withteeth shaped in this manner, line contact, if not surface contact, willbe produced between engaging'teeth under all conditions of engagement sothat wear-andpossibility of damage to the teeth are minimized. Where theteeth have straight sides as shown surface contact therebetween will bepresent as soon as the teeth have passed corner engagement. It iscontemplated, however, that under some conditions the teeth might haveacurved shape similar to an involute gear tooth in which case only linecontact would be present.

a The gears 19 and 21 may similarly be connected to the shaft through aclutch mechanism including a sleeve 36 slidably splined on theoutputshaft 17 and having axially projectingclutch teeth 37 and 38 atits opposite ends. The clutch teeth 37 may be identical to the clutchteeth 29 to mesh with clutchteeth- 39 on the gear 19. The synchronizingring 23carries short teeth 41 projecting between the clutch teeth 37 and39 and corresponding to the teeth 35. a V

The teeth 38 may be shorter axially than the-teeth 37 to mesh withcomplementary teeth 42 on the gear 21. The teeth 38 and 42 may be shapedsimilarly to the teeth .39 and 41 to provide an ejection angle and arealso formed with rounded tips to facilitate engagement when they are outof synchronism. Pressure generated by these teeth urges the gear 21axially of the output shaft 17 to engage an internal conical boretherein with a comically tapered friction surface 43 which is splined onthe shaft 17 and is held against axial shifting thereon. Normally whenthe teeth 38 and 42 are out of engagement, thesurfaee 43 can act as atapered bearing surface upon which the gear 21 rotates freely. However,when the teeth 'are moving into engagement axially, pressure exertedth'ereb'y on the .gear will shift it toward the large end of the surface43 tending to engage the friction surfaces and connect the gear throughthe friction surfaces to the shaft. This friction connection tends tosynchronize the speed of the gear with the shaft to facilitate shifting.

As noted above the gears 16, 21, and 27 are formed with helical teeth asshown so that during torque transmissionan axial force will be exertedon the gear 21 due to the tooth angle. Assuming that the input shaft'1'0is turning counter-clockwise as viewed from the left, the reverse pinion27 will also be driven counter-clockwise and will drive the gear 21clockwise. The angle of the teeth is such thattorque load between thereversepinion and the gear 21 will produce an axial thrust on the gear21 urging it to the right to help engage the friction surfaces.Therefore, as soon as any torque is transmitted by the gear, the toothreaction also tends to engage the friction surfaces to synchronize thegear speed. This action further assistsin engaging and disengaging "the4 clutch teeth 38 with the teeth 42. In an opposite manner when gear 21is overrunning, the thrust caused by the helical angle of the gear teethis in the direction which will reduce the thrust load on the taperbearing 43 thereby restoring the gear 21 to its free running condition.

The sleeves 28 and 36 are shifted in an identical man ner by shiftcollars 44 which are slidable axially on the sleeves respectively. Theshift collars 44 are formed with internal cam recesses 45 terminating attheir ends in outwardly tapered cam surfaces to receive actuating andcoupling elements shown as balls 46 which are slidable in radial boresin the sleeves. Each sleeve carries two axially spaced sets of balls asshown. The output shaft 17 on which the sleeves are slidably splined isformed with stepped cam recesses 47, 48, 49, and 51, to cooperate withthe sets of balls 46 respectively.

Each of the cam recesses 47, 48, 49, and 51, is formed as shown indetail in Figure 4 in connection with the recess '47. Each recess startswith a gradual incline'52 sloping inward to a substantially straightsurface '53 which terminates at a relatively deep pocket 54. Thepocket54 isformed by steeply sloping sides to provide ahighmechanicaladvantage locking action.

In operation, assuming that the sleeve 28 is to be shifted'to'the right,the colla'r44 thereon-will be moved to the right. During initialmovement the balls 46 at the left of the sleeve 28 will engage'the' leftend of the recess 45 so that the sleeve will be shifted with the collar.After a relatively slight movement suflicient only to bring the roundedtips of the right hand teeth 29 into engagement with the tips of theteeth on the synchronizer ring 22,

V the balls 46 will ride on the gradual incline 52 of the recess 47-andwill exert a camming force on the sleeve tending to urge it intoengagement with teeth 35 with a greater force than that exerted on thecollar -'44. After the speeds of the parts has become nearlysynchronized, the collar 44 can be moved further to the right and theteeth 29 will engage the teeth 32 and the balls will drop into thedeeper portions 54 of recess 47. At this time the left end of the collarwhich may be substantially cylindrical will engage the balls and willhold them firmly against accidental movement out of the recess eventhough the forces on the collar are extremely slight or if the internalcollar surface is cylindrical without the exertion of any force at all.Thus, the clutch teeth are held positively in engagement despite theejection angle thereon until'thec'ollar 44 is again shifted back to theleft.

, For-movement of the sleeve '28 to the left the collar '44 may beshiftedto the left. During the first part of this movement the left endof the collar will'move oif of the left handset of balls so thatthey canmove up into the r ecess'45 'andthe 'right'endof recess 45 will engagethe righthand'set'of balls to shift the sleeve to the 'left. On furthermovement'of the collar to the leftthe same action a's 'thatdescr'ibedabove 'will occur with the "right hand set 'of balls 46 andthe recess 48 tomove the left hand teeth 29 initially into engagementwith 'synchronizer teeth 35 and finally into mesh with the teeth 31.Similarly the sleeve 36 may be shifted to'the left past the synchronizer'ri'n'g'teeth*41 and into meshwith the teeth 3 9 by shifting its collar'44to the left. At" this timethe right hand set of balls 46 in the sleeve36will cooperate with the recess 51 to produce the holding action asdescribed above. Upon shifting the sleeve 36' to the right through itscollar 44 the left hand setof balls in the sleeve will engage thegradual incline of the recess 49 when the tips ofthe clutch teeth 38 and42 are in initial contact. Thus, loading may be maintained on theseteeth with a relatively small'force on the collar'44 and withouttransmission of anysubstantial shock back to the operating mechanismuntil'substantial 's'ynchronism has been achieved. At this time theteeth 38 and 42 may beshiftedfully into mesh and the'sle'eve 36"will belocked in its right hand position by engagement of the balls 46 with thedeeper part 54 of the recess 49. i

It will thus be seen that with the present invention shifting can beaccomplished in either the engaging or disengaging operation relativelyeasily even though the parts to be connected are rotating relativetoeach other. Furthermore when the parts are engaged they are held firmlyin engagement against any possibility of accidental displacement. i

While the invention has been shown and described in connection with oneparticular type of mechanism it will be understood that this has beenselected as illustrative only and is not to be taken as a definition ofthe scope of the invention, reference being had for this purpose to theappended claims.

What is claimed is:

1. In a power transmitting mechanism, a pair of coaxial relativelyrotatable parts, an annular series of clutch teeth on one of the partsconcentric therewith, a synchronizer ring frictionally engaging said oneof the parts, an annular series of teeth on the synchronizer ringprojecting radially into registry with the clutch teeth and relativelythin in an axial direction, an annular series of axially elongatedclutch teeth on the other of the parts in registry with the first'namedclutch teeth and of an axial length to pass between the teeth on thesynchronizer ring into engagement with the first named clutch teeth, theclutch teeth being tapered from their roots toward their tips to providean ejection angle, a shift collar, means operatively connecting theshift collar to one of the parts to move it axially toward and away fromthe other part, and locking means operated by movement of the shiftcollar to hold said one of the parts in a position adjacent to the otherpart with the clutch teeth in engagement.

2. In a power transmitting mechanism, a pair of coaxial relativelyrotatable parts, an annular series of clutch teeth on one of the partsconcentric therewith, a synchronizer ring frictionally engaging said oneof the parts, an annular series of teeth on the synchronizer ringprojecting radially into registry with the clutch teeth and relativelythin in an axial direction, an annular series of axially elongatedclutch teeth on the other of the parts in registry with the first namedclutch teeth and of an axial length to pass between the teeth on thesynchronizer ring into engagement with the first named clutch teeth, theclutch teeth being tapered from their roots toward their tips to providean ejection angle, a shaft on which one of the parts is axially slidableand having a locking recess therein, said last named one of the partshaving an opening extending radially therethrough, an actuating andlocking member slidable in the opening, and a shift collar slidableaxially on said last named one of the parts and having an internal camrecess therein to receive the actuating and locking member thereby toshift said part axially on the shaft and to cam the actuating andlocking member into the recess in the shaft when it is in registrytherewith to hold said part against axial movement on the shaft.

3. In a power transmitting mechanism, a pair of coaxial relativelyrotatable parts, an annular series of clutch teeth on one of the partsconcentric therewith, an annular series of clutch teeth on the other ofthe parts in registry with the first named clutch teeth, the clutchteeth being tapered toward each other to provide an ejection angle andhaving helically generated side surfaces to provide at least a linecontact therebetween in all relative engaging positions thereof, a shaftconnected to one of the parts to prevent relative rotation therebetween,means including a tapered friction surface supporting the other of theparts for rotation on the shaft and tapered in a direction such thataxial pressure on said other part tends to engage the friction surface,a shift collar slidably mounted on the shaft, means operativelyconnecting the shift collar to said one of the parts to move it axiallytoward and away from the other part, and locking means ejection angleand having helically generated side surfaces to provide at least a linecontact therebetween in all relative engaging positions thereof, a shafton which one of the parts is slidably mounted for axial movement towardand away from the other part and to which said one of the parts isconnected to prevent relative rotation therebetween, the shaft having alocking recess therein, said one of the parts having a radiallyextending opening therethrough to register with the recess when theparts are moved together with the clutch teeth in engagement, anactuating and locking member slidable in the opening, a shift collarslidable axially on said one of the parts and having an internal camrecess to receive the member thereby .to shift the part through themember and to cam the member into the recess in the shaft when it is inregistry therewith and a tapered friction surface rigid with the shaftand tapering toward said one of the parts, the other of the parts havinga tapered opening therein complementary to and fitting on the taperedsurface frictionally to engage it in response to axial pressuregenerated by the clutch teeth.

5. In a power transmitting mechanism, a pair of coaxial relativelyrotatable parts, an annular series of clutch teeth on one of the partsconcentric therewith, an annular series of clutch teeth on the other ofthe parts in registry with the first named clutch teeth, the clutchteeth being tapered toward each other to provide an ejection angle andhaving helically generated side surfaces to provide at least a linecontact therebetween in all relative engaging positions thereof, asynchronizer ring between the parts having an annular series of teeththereon projecting radially into registry with the teeth on the partsand relatively thin in an axial direction, complementary taperedfriction surfaces on the ring and one of the parts to be engaged bypressure on the ring toward said one of the parts, a shaft on which theother part is axially slidable toward and away from said one part andhaving a locking recess therein, said other part having an openingtherein to register with the recess when the parts are together with theteeth in engagement, an actuating and locking member slidable in theopening, and a shift collar slidable axially on said other part andhaving an internal cam recess to receive the member thereby to move theother part through the member and to cam the member into the recess inthe shaft when it is in registry therewith.

6. The construction of claim 5 in which the recess in the shaft has twosteps, one to receive the member when the teeth on said other part aremeshed with the teeth on the synchronizer ring only and the other toreceive the member when the teeth on the two parts are meshed.

7. In a power transmitting mechanism, a pair of coaxial relativelyrotatable parts, complementary annular series of clutch teeth on theparts to mesh when the parts are shifted axially together, the clutchteeth being tapered toward each other to provide an ejection angle andhaving rounded tips, a shaft on which one of the parts is shiftabletoward and away from the other having a two step recess therein with thefirst step terminating in an inclined cam surface, said one part havinga radial open ing therein, an actuating and locking member slidable inthe opening, and a shift collar slidable axially on said one part andhaving an internal cam recess therein to receive the member to shift thepart through the member and tourgethe member radially inward, therecess'and opening'being so positioned that themember-wilhengagetheinclin'ed cam surfa'ce"when the rounded tips :of the teeth are inengagement and will engage the-second step of the recess when the teethare in'full engagement.

. 8. In apower'transrnitting mechanism a pair of coaxial relativelyrotatable parts,*'c0mplementary .annular series of clutch teeth on theparts to mesh when the parts are shiftedaxially together, the clutchteeth being 'the second"stepbf therrecess when the teeth on the partstapered toward eachother to provide an ejection angle and having roundedtips, ashaft on'which one of the parts is shiftable toward and away fromtheotherhaving atwo step "recess therein with'the first=stepterminatingin an inclined cam surface, saidone part having -a radial openingtherein, 'an-actuating and'iookingmemberslidable in the' opening,-a-:shift collar slidable axiallyon said oneapart and hav ing aninternal 'ca'm recess'therein to receive the member to shift thepartthrough the member and to urge the-member radially inward, and asynchronizer ring between the partsfrict-ionally engaging one of theparts and having teeththereon projecting radially into registry with theteeth on the parts, the recess and opening being so positioned that themember will engage the cam surface when the teeth on-said= one part-arein initial engagement with the teeth on thel'ing and will engageRcterences Cited in the file of this patent UNITED STATES PATENTS746,764 Carhart Feb. 11, 1930 2,431,785 Wildhaber Dec. 2, 19472,-6'84Q741 Gregory July 27, 1954 FOREIGN PATENTS 8551807- Germany "Nov.17, 2

899,311 Germany Dec. 10, 1953

